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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
 LEADING EDGE FLAP SYSTEM - MAINTENANCE PRACTICES
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 1.  General_______
 A.  There are fifteen tasks in this procedure. The procedure contains these tasks:
 (1)  
The extension of the leading edge flaps

 (2)  
The retraction of the leading edge flaps

 (3)  
The extension of the leading edge flaps by pneumatic power

 (4)  
The retraction of the leading edge flaps by pneumatic power

 (5)  
The extension of the leading edge flaps by electrical power

 (6)  
The retraction of the leading edge flaps by electrical power

 (7)  
The deactivation of the retracted leading edge flaps

 (8)  
The activation of the retracted leading edge flaps

 (9)  
The deactivation of the extended leading edge flaps and the installation of the safety locks

 (10)
 The removal of the safety locks and the activation of the extended leading edge flaps

 (11)
 The extension of the leading edge flaps with PDU not serviceable (alternate drive motor brake serviceable)

 (12)
 The extension of the leading edge flaps with PDU not serviceable (alternate drive motor brake not serviceable)

 (13)
 The extension of the leading edge flaps with PDU not serviceable (a broken annunicator switch actuator)

 (14)
 The removal of the flap lever lock

 (15)
 The installation of the flap lever lock.

 B.  
It is possible to extend or retract the leading edge (LE) flaps accidentally. This can cause injury to persons or damage to equipment. The LE flaps will operate in four different modes:

 (1)  
The flap control lever controls the operation of the LE flaps in the primary pneumatic mode.

 (2)  
The flap control lever also controls the operation of the LE flaps in the primary electric mode.

 (3)  
The alternate flaps control switches controls the operation of the LE flaps in the alternate electric mode.

 (4)  
The reverse thrust levers control the operation of the Group A LE flaps in the reverse thrust pneumatic mode.

 C.  
In primary pneumatic or primary electric mode, the group A LE flaps extend when you move the flap control lever to the 1 unit position. The group B LE flaps extend when you move the flap control lever to the 5 unit position. Move the flap control lever back to the 1 unit detent. The group B LE flaps will retract as soon as the inboard trailing edge flaps retract to less than 5 units. Move the flap control lever to the UP position. The group A LE flaps will retract as soon as the outboard TE flaps retract.

 D.  
In alternate electric mode, the LE flaps extend when the ALTN FLAPS ARM switch is in ARM and the ALTN FLAPS EXT/RET switch is in EXT. When the ALTN FLAPS EXT/RET switch is in the RET position, the LE flaps retract as soon as the inboard TE flaps retract fully.

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 27-81-00
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

 E.  In reverse thrust pneumatic mode, the Group A LE flaps will retract automatically if you operate the reverse thrust levers 1 and 4 or 2 and 3. The Group A LE flaps will extend when you put the reverse thrust levers in the idle position. There is no automatic retraction/extension if the system is not in primary pneumatic mode.
 F.  Before you supply pneumatic power to the airplane, make sure the area around the leading edge flaps is clear of all persons and equipment. The leading edge flaps can move automatically when you supply pneumatic power.
 G.  Leading edge flaps must be deactivated when there will be persons in the area of the wing leading edge. Also install safety locks if the leading edge flaps are extended.
　
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